Field
The present specification generally relates to processes for chemically strengthening glass, and more particularly, to low-temperature processes for chemically strengthening glass. Even more particularly, the present specification relates to low-temperature processes for chemically strengthening glass in an ion exchange solution that includes additives.
Technical Background
Chemically strengthened glass has recently been used in hand held devices, such as mobile phones, media players, and other devices, as well as other applications requiring high strength and abrasion resistance.
Ion exchange is a chemical strengthening process that starts with a glass containing smaller ions (effluent ions) that are capable of being exchanged with larger ions (exchange ions) in an ion exchange solution at elevated temperatures. In the ion exchange process, the larger exchange ions replace the smaller effluent ions in the glass. The larger, densely packed ions at the glass surface generate a high compressive stress, which in turn provides higher strength.
Conventionally, the temperature of the ion exchange solution during the ion exchange process is between 370° C. and 550° C. to strengthen glass for consumer product applications. The high temperatures required in conventional ion exchange processes can result in the breakdown of salts in the ion exchange solution forming byproducts that may have an effect on the visual properties of the glass and, in some cases, can be caustic.
Accordingly, a need exists for low-temperature ion exchange processes.